The background of the invention will be set forth in two parts.
1. Field of the Invention
This invention relates to parametric amplifiers and more particularly to balanced synchronous parametric amplifiers.
2. Description of the Prior Art
In recent years there has been a growing interest in what are known as small earth terminals for satellite communications systems. The heart of such terminals is a phase-locked parametric receiver which receives, for example, television signals from a satellite through a relatively small antenna. Such a receiver must have wide bandwidth characteristic with a minimum of time delay. Wide bandwidth is required for reception of high deviation full bandwidth television signals for which the system is designed.
The phase-locked parametric receiver incorporates a phase control loop which is closed through a parametric amplifier. It is essential for stable operation that the loop time delay be minimized and thus, in particular, that time delay in the parametric amplifier be held as small as possible.
While phase-locked receivers using a synchronously-pumped parametric amplifier are known in the art, such receivers have not been used for wideband signals because of the difficulty of achieving sufficiently small loop delays for stable operation. It should, therefore, be evident that a new technique which provides wide bandwidth and minimum time delay in a parametric amplifier would constitute a significant advancement of the art.